In a small bowl or glass mason jar, whisk together the Champagne vinegar, Dijon mustard, minced garlic, mayonnaise, salt, and pepper.While whisking, slowly add in the olive oil until the vinaigrette is emulsified.Use the dressing now or cover and store it in the refrigerator. This dressing will last 2 days. Make sure to shake or whisk it well before using.Let's prep for salad. Get out a large salad bowl and toss in your mixed greens. Thinly slice and add in the romaine lettuce. I prefer to chop up my romaine lettuce rather than tear it up because to me it's just easier, and the leaves are more uniform in size.Dice up the red pepper and avocado and chop up the tomato. Feel free to add some thinly sliced red onion, radishes as well as cucumber. Really, make this your own salad and toss in whatever greens and veggies you want!This dressing will last 2 days. Make sure to shake or whisk it well before using.